An engine control module of an internal combustion engine controls the mixture of fuel and air supplied to combustion chambers within cylinders of an engine. After the air/fuel mixture is ignited, combustion takes place and later the combustion gases exit the combustion chambers through exhaust valves. The combustion gases are directed by an exhaust manifold to a catalytic converter or other components of an exhaust aftertreatment system. Some engines optionally may include a forced air induction device, such as a turbocharger, that is positioned between the exhaust manifold and exhaust aftertreatment components.
Manufacturers of internal combustion engines, particularly diesel engines, are presented with the challenging task of complying with current and future emission standards for the release of nitrogen oxides, particularly nitrogen monoxide, as well as unburned and partially oxidized hydrocarbons, carbon monoxide, particulate matter, and other particulates. In order to reduce the emissions of internal combustion engines, an exhaust aftertreatment system is used to reduce these constituents from the exhaust gas.
Exhaust gas aftertreatment systems typically include one or more aftertreatment devices, such as particulate filters, catalytic converters, mixing elements and urea/fuel injectors. Control of temperature of the exhaust gas can affect the performance of components within the exhaust system. For example, a particulate filter is configured to remove carbon particles or particulates that result from incomplete combustion of a hydrocarbon fuel, also referred to as soot, from the exhaust gas. Particulate filters are typically designed to accumulate a selected amount of soot within the device. Particulate filters may be configured to periodically burn off the accumulated soot through a regeneration process. The regeneration process may be initiated by increasing a temperature of the exhaust gas entering the particulate filter, wherein the elevated temperature causes the soot to burn. Thus, accurate control of the exhaust gas temperature at selected locations in the exhaust system can lead to improved performance and reduced emissions.